Field of the Invention
The present invention relates generally to a sterile, pharmaceutical composition inserted into a dental handpiece prior to and after sterilization to lubricate moving parts and to inhibit handpiece corrosion, and, more particularly, to the process of sterilizing such instruments by inserting such compositions prior to auto-claving.
a. Prior Handpiece Lubricants and Processes
It is well known that a dental handpiece has to be lubricated periodically to maintain its efficiency and prevent premature failure. The rotor or turbine in the handpiece is supported in bearings which are subjected to severe wear due to the wide range of speeds and torque loads involved in drilling teeth. Typically, the bearings are lubricated by adding oil in a variety of ways, such as from a large oiler connected to the rotor drive air feed line which intermittently drops oil into the inlet air stream where the oil is atomized and then carried to the rotor entrained in the inlet air.
In a method disclosed in Sugai U.S. Pat. No. 4,218,216 an improved system employed a small oiler inserted in the air feed line having a spring loaded check valve overcome by feed air pressure to allow oil to escape into the feed air, be atomized and continuously lubricate the rotor bearings. However, with the onset of AIDS and the need for increased sterilization, such a system did not function during auto-claving and offered no protection against cross contamination.
By 1991, as disclosed in Feldman U.S. Pat. No. 5,131,845, it was highly recommended that the handpiece be sterilized frequently, and sterilization of the handpiece between patients was becoming a recommended procedure. However, increased sterilization required more frequent lubrication. It was known to lubricate the handpiece both before and after sterilization.
However, the initial lubricants used pre-sterilization and post-sterilization were generally the same products as were previously available prior to the need for increased sterilization. These products did not survive the heat of the auto-clave process itself and were ineffective. Handpiece failures increased and were replaced at an average unit cost of about $150.00.
While Feldman developed an improved method of inserting the oil into the rotor drive air feed line using a squeezable sealed capsule containing the lubricant and his system further prevented the transmission of viral and bacterial matter to the patient and the dentist, it did not advance the art of developing lubricant compositions that could not only withstand the auto-clave cycle, but also, protect the handpiece during the auto-clave cycle by retaining and/or enhancing their boundary lubricating and anti-corrosion characteristics. Feldman merely disclosed that his shell 10 was filled with an extremely light, dental grade, FDA approved, lubricating oil which was required for the handpiece and widely used in the art. Feldman 7:21-24.
b. Industrial Product Preservatives
It was also known to add ingredients, such as, an anion selected from the group consisting of sulfate, acetate and citrate groups, to aqueous industrial products to inhibit microbiological degradation in such products resulting from the growth of micro-organisms which can cause odors, deterioration and corrosion. Pera U.S. Pat. No. 4,920,107. In an improvement to Nelson U.S. Pat. No. 5,283,005, the biocidal efficacy of such additives were enhanced by mixing a known preservative (pyrithione, used in lubricants) with a known antibiotic (lipopeptide, for treating superficial infections) to inhibit notably bacteria and fungi from forming in the composition itself when used alone or in combination with an inert carrier, such as water, liquid hydrocarbons, ethanol, isopropanol, or the like. 2:63-67. However, there was no disclosure or suggestion of the composition of the present invention, that the disclosed compositions were sterile or could be used as pre-sterilization lubricants for a dental handpiece, or that the boundary lubricating or protective quality of the compositions were enhanced.
c. Boundary Lubricant Theory
The general theory of how a boundary lubricant works is well known. When surfaces contact each other during rolling or sliding contact, wear particles are formed which combine with the lubricant to form an eutectic film (the new material has a lower melting point than the original material) which can withstand high loads and become the sacrificial layer which is worn away and removed instead of the underlying (rotor/bearing) material, thus, reducing friction.
It is an object of the present invention to provide a new, low coefficient of friction, lubricant composition and process that allows insertion of the composition into the rotor drive air inlet prior to the auto-clave cycle, or after, or both, and which remains effective during the auto-clave cycle and thereafter to provide improved protection of the handpiece against corrosion, substantially reduced wear rates and substantially improved resistance to wear, thereby extending significantly the service life of the handpiece.
It is a further objective of the present invention to provide a new sterile composition and process that reduces the risk of cross contamination from viruses and bacteria.